Spray painting apparatus



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June 28, 1960 BQK r 2,942,787

SPRAY PAINTING APPARATUS Filed June 11, 1959 ,2 Ellll BY 7 j g-m 5mmATTORNEY 2,942,787 r ICC n e June 28, teen ni ed a e P R0ckville,Md.)

Filed June 11, 1959, Ser. No. 819,643 Claims. (Cl. 239-124) The presentinvention relates to a spray painting apparatus of the type whichevaporates a volatile thinner for the paint and utilizes the vapor soobtained as a spraying medium, particularly. such an apparatus whereinthe painttobe sprayed is preheated by its delivery adjacent the hotvapor spraying medium.

The instant invention is related to application Serial No. 798,509,filed by the inventors herein on March 10, 1959, for a Paint SprayingApparatus. In this prior application, the paint to be sprayed waspreheated by its momentary passage through a heat exchanger which wasadapted principally for evaporation of the spraying medium.

The instant invention distinguishes from the aforesaid application andthe art-in that heat exchange between the spraying medium and the paintto be sprayed is not limited to juxtaposed contact within an evaporationdevice. Rather, heat exchange between the vapor spraying medium and thepaint to be sprayed is effected intermediate .the evaporation device andthe spray painting gun byan abutting of the vapor spraying circuit andthe paint supply circuit. This heat exchange is enhanced by theemployment of a vapor return wherein small amounts of vapor are returnedcontinuously from said spray gun to a condensing coil and thence to theevaporation device. l a.

Theinstant invention also embodies paint supply pres-. surizingrneans,'utilizing CO or like volatile matter, whereby the paint is urgedtowards the spray painting 81 I V 'As indicated above, the instantinvention embodies also a vapor condensing coil, located in a returnportion of the vapor circuit and juxtaposed and interconnected withvolatile liquid supplyconduit. This vapor condenser coil is immersed inliquid cooling means, which, together with. the juxtaposed volatileliquid supply conduit, enhance condensation. This enhanced condition forcondensation assures that only liquid matter is returned to theevaporation. device...

. Manifestly, the instant invention assures the efiicacious spraying ofhot painttogether with a hot vaporous thinner with a resultantcapabilityof achieving lower viscosity paint at the point. of its.contact with the object to be sprayed... Theadvantages of this inventionover conventional;deyiceswherein-hot paint is sprayed by cold air meansor the like are obvious. Since lower viscosities are provided at thepoint of spray contact, a.

higher viscosity paint may be employed effectively in this apparatus.

Accordingly, it is an object of invention to provide in a spray paintingapparatus, means for pre-heating the paint to be sprayed.

Another object of invention is to provide in a spray a ing medium.

Andther'objectof'invention is to provide in a spraypainting apparatusmeans for returning the spray paint-1 I :Anotherobject of invention isto provide in aspray painting apparatus means forreturning, condensingand reusing portions of the spray painting medium;

' Yettother objects of invention will 'become apparent from the ensuingspecification and -attached drawings, wherein: p T

Fig. l is a schematic view of the instant spray painting apparatus,embodying a spray paint gun, a pressure tank having a heating "elementmounted therein, a sourceof paint supply, and a pressurizing-mediumadjacent thereto,- a source of volatile liquid to be employed as thespray! ingmedium and a vapor condensing coil juxtaposed andinterconnecting witha spraying medium supply line lead! ing from saidsource ofspraying medium to said pressure tank.

Fig. 2 is a cross section offthe vapor circuit and paint circuitabuttingly disposed within an insulated cover for heat exchange.

In Fig. 1 a pressure vessel is shown as having an electric heatingelement 2 fixed therein, and containing a volatile hydrocarbonliquid 3;Vapor compartment 4 in the top interiorof the evaporation. device isdefined by a volatile liquid 3 level. The pressure vessel may be mountedwithin a suitable casing, indicated by dotted lines 5. A vapor circuitleading from vapor compante ment 4 comprises vapor supply conduit 6which'leads to spray painting gun Shaving head 7, and vapor returncircuit 9. As indicated in applicants aforesaid application, a portionof generated vapor may be returned continuously through. the spray gunto the pressure vessel for purposes-of heating thespray gun so as toavoidjcondensation ofspraying medium therein;

conduit9 wliich leads "to condensing device 11, eomprisleads fromyolatile liquid supply-tank .15 containing ,a'

volatile hydrocarbonor like liquid 17. As will be apparent, water-13, aswellas volatile liquid 17 within. coil 18 cause-condensation within-coil12,'thus assuring that? matter returned. through suction conduit 14 isin con- 1 densedformu Gearpump 20 powered by motor Zl may be-employed toeifect .a suction return through conduit 14, thence into inlet '22 ofthe evaporationdevice 2.

. A paintcontainer 213 is shown as having outlet tube24, outlet valve25,10 which is connected paint conduitjfl.

1 Paint conduit 33 is attached to flexible paint supply hose- 34, whichas shown in Fig.2 abuts both vapor supply circuit 6 and vapor returncircuit 9. Thus, paint'2 6 carried in hose 34 is preheated prior to itsentry within spray gunfheadfl. 7 V 1 {:AS illustrated in Fig.1, a paintpressurizing container 27, containing .:CO or otherhighly volatileliquid may. beemployed" Container27 is connected to paint coutainer' 2s,.vnf; va11 ve,.-29, jnlet co duit 30-and pressure,

regulator 31 affording regulated pressure of 'gas upon paint 26. Thus,there is a constant pressure'in top compartment 32 of container 23 whichpressure urges paint 26 outwardly through outlet tube 24 and intoconduits 33 and 34 for spraying purposes.

As shown in Fig.2 abutting vapor circuits- 6 and 9' sprayingis achieved;with iconsequenti savings amount of paint employed, :1 w '1 i' .7 Theforegoing description and attacheddrawings are,

7 Q is 3 even and more complete coat of paint upon the spray surface.Manifestly, it eliminates the necessity for repetitive spraying of asingle surface. Thus, improvedpaint I mediate said pressure tank and theabuttal of said vapor submitted asillustrative'bnlyi of aproposed-construction 1. A spray painting. apparatus comprising apressure tank adapted to'contain volatile "liquid; an electric re'sistor mounted in said tank; means-defining an inlet forsaid liquid-insaid tank; means defining' a vapor outlet in said tank; a main vaporcircuit, including a conduit co nected with said vapor outlet in 'said'tank; a spray gun connected with said conduit; and a paint supply {tankhavinga paint outlet and a paint circuit interconnecting said paintoutlet and said spray gun, said paint circuit abutting said main vaporcircuit.

' 2. 'A spray painting apparatus as in claim 1 ,"said rnain 7 I V apaint carried in said paint supply conduit.

4.A spray painting apparatus comprising a pressure tank having aresistanceheat'ing element for evaporating a volatile paint thinner'mounted in said tank; a vapor circuit attached to said tank andincluding at an intermediate portion a'spray-gumfa paint supply-tank;and

circuit and said paint circuit.

7. A spray painting apparatus comprising a source of supply of volatileliquid; a pressure tank adapted for evaporation of said liquid; aheating element mounted in'said pressure tank; 'a yo'latile liquidsupply conduit leading from said source of supply to saidpressure tank;

: a main vapor circuit leading from' said pressuretank to -a spray paintgun and from thence to a vnpor condensing coil mounted insaidvolatileliquid supply-conduit;,said vapor condensing coil beingjuxtaposed with. a volatile liquid supply coil. 7 v

I -8. A spray painting apparatus at source of supply of volatile liquid;a pressure tank adapted for evaporation of said liquid; a heatingelement mounted in said pressure tank; a volatile liquid'supply conduitleading from said source of supply to said pressure tank; a

a paint circuit leading from said tank to said spray gun and abuttingsaid vapor circuit for preheating of paint tobesprayed.

' SJAsprayxpainting apparatus comprisinga pressure tank'adaptedtocontain a volatile liquidjan electricresistor mounted in said tank;means defining an inlet .for

. said liquid in said tank; meansf de'fining a yaporyoutlet in said'tank; a main vapor circuit, including a conduit connected withsaidvapor outlet in 'said'ft' alk; a spray gun'connected with saidconduit; a paint supply tank having a paint outlet, a paint circuitconnected to said paint outlet and said spray gun, said paint circuit"substantially abutting said main vapor ,c'ircuit; and'pressurizingmeans adjacent said paint supply tank and urging said paint into saidpaint outlet.y v a main vapor circuit leading from said pressure tank toa spray, paint gun and from thence to a vapor condensing coil mounted insaid volatile liquid supply conduit said vapor'condensing coil beingjuxtaposed with a volatile liquid supply conduit coil, and beingimmersed in liquid cooling means.

9. A'spray painting apparatus comprising .a source of volatile liquid; asource of paint; a pressure tank having a heating element mountedtherein for evaporating. said volatile liquid; a volatile liquidrsupplyconduit interconne'cting said source of volatile liquid and saidpressure tank; a vapor circuit leading from said pressure tank to apaint spray gun and from thence to a condensing coil immersed 'incooling liquid, said condensing coil being juxtaposed and connected tosaid volatile liquid supply conduit; and a paint supply conduit leadingfrom said source of paint to said spray gun and said paint supplyconduit abutting said vapor circuit for preheating of paint carriedtherein. a a r a 1 0 A spraypainting apparatus comprising a source 'ofvolatile liquid;'a source of paint; a' pressure (tank having a heatin gelenient mounted therein for evaporating said volatile liquid; avolatileliquid supply conduit interto a paint spray gunrand from thenceto a condensing 6. A spray painting apparatus comprising a pressure 7tank'adapted ,to contain a volatile liquid; an electric resistor mountedin said tank; means defining an inlet-for said liquid in said tank;means defining avapor outlet in said tank; a main vapor circuitincluding a.conduit having a paint outlet; a paint circuit connected "tosaid paint outlet and said spray gun, said paint circuit sub-Vstantially abutting said mainrvapor circuit; and a vapor condensing coilmounted in said main vapor circuit inter coil 'immersed'in coolingliquid, said condensing'coillbeing juxtaposed and-connected to saidvolatilegliquid supply conduit; and a paint'supply conduitlea'ding'from' said source of paint to said spray gun via said pressurevessel for preheating paint carried therein, j,

References Cited in the file of this patent V p UNITED STATES PATENTS v2,016,407 Wentzel' OctZ S," 1935 2,123,604 Johnson .i July 12, 19382,378,184 a Carlson "L 1Iune :12, 1-945

